Wholly aromatic polyester resins have long been known. For instance, 4-hydroxybenzoic acid homopolymer and copolymers have been provided in the past and are commercially available. Such polymers commonly are crystalline in nature, relatively high melting or possess a decomposition temperature which is below the melting point, and when molten frequently exhibit an isotropic melt phase. Molding techniques such as compression molding or sintering may be utilized with such materials. Representative publications which discuss these wholly aromatic polyesters include: (a) Polyesters of Hydroxybenzoic Acids, by Russell Gilkey and John R. Caldwell, J. of Applied Polymer Sci., Vol. II, Pages 198 to 202 (1959), (b) Polyarylates (Polyesters From Aromatic Dicarboxylic Acids and Bisphenols), by G. Bier, Polymer, Vol. 15, Pages 527 to 535 (August 1974), (c) Aromatic Polyester Plastics, by S. G. Cottis, Modern Plastics, Pages 62 to 63 (July 1975), and (d) Poly(p-Oxybenzoyl Systems): Homopolymer for Coatings: Copolymers for Compression and Injection Molding, by Roger S. Storm and Steve G. Cottis, Coatings Plast. Preprint, Vol. 34, No. 1, Pages 194 to 197 (April 1974). See also, U.S. Pat. Nos. 3,039,994; 3,169,121; 3,321,437; 3,553,167; 3,637,595; 3,651,014; 3,662,052; 3,668,300; 3,723,388; 3,759,870; 3,767,621; 3,773,858; 3,787,370; 3,790,528; 3,829,406; 3,857,814; 3,884,876; 3,890,256; 3,974,250; and 3,975,487. U.K. patent application No. 2,058,102A which was published on Apr. 8, 1981, discusses the use in ovenware of a broadly defined class of polyesters which may include oxynaphthoyl moieties of unspecified symmetry.
Wholly aromatic polyesters additionally have been disclosed which incorporate 6-oxy-2-naphthoyl moieties and which are stated to exhibit an optically anisotropic melt phase. See, for instance, commonly assigned U.S. Pat. Nos. 4,161,470; 4,219,461; 4,256,624; 4,279,803, 4,299,756; and 4,318,841; and commonly assigned U.S. Ser. No. 169,014, filed July 15, 1980 (now U.S. Pat. No. 4,337,190). Commonly assigned U.S. Ser. Nos. 214,557, filed Dec. 9, 1980 (now U.S. Pat. No. 4,330,457); 251,625, filed Apr. 6, 1981 (now U.S. Pat. No. 4,351,917); and 251,629, filed April 6, 1981 (now U.S. Pat. No. 4,351,918), disclose poly(ester-amides) which incorporate 6-oxy-2-naphthoyl moieties. Commonly assigned U.S. Ser. No. 319,024, filed Nov. 6, 1981, discloses a poly(ester-carbonate) which incorporates 6-oxy-2-naphthoyl moieties.
It is an object of the present invention to provide an improved thermally stable polymer.
It is an object of the present invention to provide an improved thermally stable polymer which is particularly suited for use in the formation of plasma spray coatings, compression molded articles, and impact molded articles.
It is an object of the present invention to provide a novel polymer which exhibits good mechanical strength at elevated temperatures, good resistance to flow and creep at elevated temperatures, good wear resistance at elevated temperatures, and good resistance to flammability.
It is an object of the present invention to provide a novel polymer which has been found to exhibit a thermal stability which is superior to that of poly(4-oxybenzoate) formed under the same conditions.
It is an object of the present invention to provide a novel polymer which has been found to exhibit a higher level of crystallinity than poly(4-oxybenzoate) formed under the same conditions.
It is a further object of the present invention to provide a novel polymer which has been found to exhibit a crystal/crystal transition in the solid state at a higher temperature than poly(4-oxybenzoate) formed under the same conditions.
These and other objects, as well as the scope, nature, and utilization of the claimed invention will be apparent to those skilled in the art from the following detailed description and appended claims.